* The default value we give to the environment variable LESS has been
changed from "FRSX" to "FRX", losing "S" (chop long lines instead
of wrapping). Existing users who prefer not to see line-wrapped
output may want to set

$ git config core.pager "less -S"

to restore the traditional behaviour. It is expected that people
find output from most subcommands easier to read with the new
default, except for "blame" which tends to produce really long
lines. To override the new default only for "git blame", you can
do this:

$ git config pager.blame "less -S"

* A few disused directories in contrib/ have been retired.

Updates since v2.0
------------------

UI, Workflows & Features

* Since the very beginning of Git, we gave the LESS environment a
default value "FRSX" when we spawn "less" as the pager. "S" (chop
long lines instead of wrapping) has been removed from this default
set of options, because it is more or less a personal taste thing,
as opposed to the others that have good justifications (i.e. "R" is
very much justified because many kinds of output we produce are
colored and "FX" is justified because output we produce is often
shorter than a page).

* The logic and data used to compute the display width needed for
UTF-8 strings have been updated to match Unicode 7.0 better.

* HTTP-based transports learned to better propagate the error messages from
the webserver to the client coming over the HTTP transport.

* The completion script for bash (in contrib/) has been updated to
better handle aliases that define a complex sequence of commands.

* The "core.preloadindex" configuration variable is enabled by default,
allowing modern platforms to take advantage of their
multiple cores.

* "git clone" applies the "if cloning from a local disk, physically
copy the repository using hardlinks, unless otherwise told not to with
--no-local" optimization when the url.*.insteadOf mechanism rewrites a
remote-repository "git clone $URL" into a
clone from a local disk.

* The `core.commentChar` configuration variable is used to specify a
custom comment character (other than the default "#") for
the commit message editor. This can be set to `auto` to attempt to
choose a different character that does not conflict with any that
already starts a line in the message being edited, for cases like
"git commit --amend".

* "git format-patch" learned --signature-file=<file> to add the contents
of a file as a signature to the mail message it produces.

* "git grep" learned the grep.fullname configuration variable to force
"--full-name" to be the default. This may cause regressions for
scripted users who do not expect this new behaviour.

* "git log" and friends now understand the value "auto" for the
"log.decorate" configuration variable to enable the "--decorate"
option automatically when the output is sent to tty.

* "git merge" without an argument, even when there is an upstream
defined for the current branch, refused to run until
merge.defaultToUpstream is set to true. Flip the default of that
configuration variable to true.

* "git mergetool" learned to drive the vimdiff3 backend.

* mergetool.prompt used to default to 'true', always asking "do you
really want to run the tool on this path?". The default has been
changed to 'false'. However, the prompt will still appear if
mergetool used its autodetection system to guess which tool to use.
Users who explicitly specify or configure a tool will no longer see
the prompt by default.

Strictly speaking, this is a backward incompatible change and
users need to explicitly set the variable to 'true' if they want
to be prompted to confirm running the tool on each path.

* "git replace" learned the "--edit" subcommand to create a
replacement by editing an existing object.

* "git replace" learned a "--graft" option to rewrite the parents of a
commit.

* "git send-email" learned "--to-cover" and "--cc-cover" options, to
tell it to copy To: and Cc: headers found in the first input file
when emitting later input files.

* "git svn" learned to cope with malformed timestamps with only one
digit in the hour part, e.g. 2014-01-07T5:01:02.048176Z, emitted
by some broken subversion server implementations.

* "git tag" when editing the tag message shows the name of the tag
being edited as a comment in the editor.

* "git tag" learned to pay attention to "tag.sort" configuration, to
be used as the default sort order when no --sort=<value> option
is given.

* A new "git verify-commit" command, to check GPG signatures in signed
commits, in a way similar to "git verify-tag" is used to check
signed tags, was added.

Performance, Internal Implementation, etc.

* Build procedure for 'subtree' (in contrib/) has been cleaned up.

* Support for the profile-feedback build, which has
bit-rotted for quite a while, has been updated.

* An experimental format to use two files (the base file and
incremental changes relative to it) to represent the index has been
introduced; this may reduce I/O cost of rewriting a large index
when only small part of the working tree changes.

* Effort to shrink the size of patches Windows folks maintain on top
by upstreaming them continues. More tests that are not applicable
to the Windows environment are identified and either skipped or
made more portable.

* The `core.deltabasecachelimit` used to default to 16 MiB , but this
proved to be too small, and has been bumped to 96 MiB.

* "git blame" has been optimized greatly by reorganising the data
structure that is used to keep track of the work to be done.

* "git diff" that compares 3-or-more trees (e.g. parents and the
result of a merge) has been optimized.

* The API to update/delete references are being converted to handle
updates to multiple references in a transactional way. As an
example, "update-ref --stdin [-z]" has been updated to use this
API.

* skip_prefix() and strip_suffix() API functions are used a lot more
widely throughout the codebase now.

* Parts of the test scripts can be skipped by using a range notation,
e.g. "sh t1234-test.sh --run='1-4 6 8-'" to omit test piece 5 and 7
and run everything else.

Also contains various documentation updates and code clean-ups.

Fixes since v2.0
----------------

Unless otherwise noted, all the fixes since v2.0 in the maintenance
track are contained in this release (see the maintenance releases'
notes for details).

* We used to unconditionally disable the pager in the pager process
we spawn to feed out output, but that prevented people who want to
run "less" within "less" from doing so.
(merge c0459ca je/pager-do-not-recurse later to maint).

* Tools that read diagnostic output in our standard error stream do
not want to see terminal control sequence (e.g. erase-to-eol).
Detect them by checking if the standard error stream is connected
to a tty.
(merge 38de156 mn/sideband-no-ansi later to maint).

* Mishandling of patterns in .gitignore that have trailing SPs quoted
with backslashes (e.g. ones that end with "\ ") has been
corrected.
(merge 97c1364be6b pb/trim-trailing-spaces later to maint).

* Reworded the error message given upon a failure to open an existing
loose object file due to e.g. permission issues; it was reported as
the object being corrupt, but that is not quite true.
(merge d6c8a05 jk/report-fail-to-read-objects-better later to maint).

* "git log -2master" is a common typo that shows two commits starting
from whichever random branch that is not 'master' that happens to
be checked out currently.
(merge e3fa568 jc/revision-dash-count-parsing later to maint).

* Code to avoid adding the same alternate object store twice was
subtly broken for a long time, but nobody seems to have noticed.
(merge 80b4785 rs/fix-alt-odb-path-comparison later to maint).
(merge 539e750 ek/alt-odb-entry-fix later to maint).

* The "%<(10,trunc)%s" pretty format specifier in the log family of
commands is used to truncate the string to a given length (e.g. 10
in the example) with padding to column-align the output, but did
not take into account that number of bytes and number of display
columns are different.
(merge 7d50987 as/pretty-truncate later to maint).

* "%G" (nothing after G) is an invalid pretty format specifier, but
the parser did not notice it as garbage.
(merge 958b2eb jk/pretty-G-format-fixes later to maint).

* A handful of code paths had to read the commit object more than
once when showing header fields that are usually not parsed. The
internal data structure to keep track of the contents of the commit
object has been updated to reduce the need for this double-reading,
and to allow the caller find the length of the object.
(merge 218aa3a jk/commit-buffer-length later to maint).

* The "mailmap.file" configuration option did not support tilde
expansion (i.e. ~user/path and ~/path).
(merge 9352fd5 ow/config-mailmap-pathname later to maint).

* The completion scripts (in contrib/) did not know about quite a few
options that are common between "git merge" and "git pull", and a
couple of options unique to "git merge".
(merge 8fee872 jk/complete-merge-pull later to maint).

* The unix-domain socket used by the sample credential cache daemon
tried to unlink an existing stale one at a wrong path, if the path
to the socket was given as an overlong path that does not fit in
the sun_path member of the sockaddr_un structure.
(merge 2869b3e rs/fix-unlink-unix-socket later to maint).

* An ancient rewrite passed a wrong pointer to a curl library
function in a rarely used code path.
(merge 479eaa8 ah/fix-http-push later to maint).

* "--ignore-space-change" option of "git apply" ignored the spaces
at the beginning of lines too aggressively, which is inconsistent
with the option of the same name that "diff" and "git diff" have.
(merge 14d3bb4 jc/apply-ignore-whitespace later to maint).

* "git blame" miscounted the number of columns needed to show localized
timestamps, resulting in a jaggy left-side-edge for the source code
lines in its output.
(merge dd75553 jx/blame-align-relative-time later to maint).

* "git blame" assigned the blame to the copy in the working-tree if
the repository is set to core.autocrlf=input and the file used CRLF
line endings.
(merge 4d4813a bc/blame-crlf-test later to maint).

* "git clone -b brefs/tags/bar" would have mistakenly thought we were
following a single tag, even though it was a name of the branch,
because it incorrectly used strstr().
(merge 60a5f5f jc/fix-clone-single-starting-at-a-tag later to maint).

* "git commit --allow-empty-message -C $commit" did not work when the
commit did not have any log message.
(merge 076cbd6 jk/commit-C-pick-empty later to maint).

* "git diff --find-copies-harder" sometimes pretended as if the mode
bits have changed for paths that are marked with the assume-unchanged
bit.
(merge 5304810 jk/diff-files-assume-unchanged later to maint).

* "filter-branch" left an empty single-parent commit that results when
all parents of a merge commit get mapped to the same commit, even
under "--prune-empty".
(merge 79bc4ef cb/filter-branch-prune-empty-degenerate-merges later to maint).

* "git format-patch" did not enforce the rule that the "--follow"
option from the log/diff family of commands must be used with
exactly one pathspec.
(merge dd63f16 jk/diff-follow-must-take-one-pathspec later to maint).

* "git gc --auto" was recently changed to run in the background to
give control back early to the end-user sitting in front of the
terminal, but it forgot that housekeeping involving reflogs should
be done without other processes competing for accesses to the refs.
(merge 62aad18 nd/daemonize-gc later to maint).

* "git grep -O" to show the lines that hit in the pager did not work
well with case insensitive search. We now spawn "less" with its
"-I" option when it is used as the pager (which is the default).
(merge f7febbe sk/spawn-less-case-insensitively-from-grep-O-i later to maint).

* We used to disable threaded "git index-pack" on platforms without
thread-safe pread(); use a different workaround for such
platforms to allow threaded "git index-pack".
(merge 3953949 nd/index-pack-one-fd-per-thread later to maint).

* The error reporting from "git index-pack" has been improved to
distinguish missing objects from type errors.
(merge 77583e7 jk/index-pack-report-missing later to maint).

* "log --show-signature" incorrectly decided the color to paint a
mergetag that was and was not correctly validated.
(merge 42c55ce mg/fix-log-mergetag-color later to maint).

* "log --show-signature" did not pay attention to the "--graph" option.
(merge cf3983d zk/log-graph-showsig later to maint).

* "git mailinfo" used to read beyond the ends of header strings while
parsing an incoming e-mail message to extract the patch.
(merge b1a013d rs/mailinfo-header-cmp later to maint).

* On a case insensitive filesystem, merge-recursive incorrectly
deleted the file that is to be renamed to a name that is the same
except for case differences.
(merge baa37bf dt/merge-recursive-case-insensitive later to maint).

* Merging changes into a file that ends in an incomplete line made the
last line into a complete one, even when the other branch did not
change anything around the end of file.
(merge ba31180 mk/merge-incomplete-files later to maint).

* "git pack-objects" unnecessarily copied the previous contents when
extending the hashtable, even though it will populate the table
from scratch anyway.
(merge fb79947 rs/pack-objects-no-unnecessary-realloc later to maint).

* Recent updates to "git repack" started to duplicate objects that
are in packfiles marked with the .keep flag into the new packfile by
mistake.
(merge d078d85 jk/repack-pack-keep-objects later to maint).

* "git rerere forget" did not work well when merge.conflictstyle
was set to a non-default value.
(merge de3d8bb fc/rerere-conflict-style later to maint).

* "git remote rm" and "git remote prune" can involve removing many
refs at once, which is not a very efficient thing to do when very
many refs exist in the packed-refs file.
(merge e6bea66 jl/remote-rm-prune later to maint).

* "git log --exclude=<glob> --all | git shortlog" worked as expected,
but "git shortlog --exclude=<glob> --all", which is supposed to be
identical to the above pipeline, was not accepted at the command
line argument parser level.
(merge eb07774 jc/shortlog-ref-exclude later to maint).

* The autostash mode of "git rebase -i" did not restore the dirty
working tree state if the user aborted the interactive rebase by
emptying the insn sheet.
(merge ddb5432 rr/rebase-autostash-fix later to maint).

* During "git rebase --merge", a conflicted patch could not be
skipped with "--skip" if the next one also conflicted.
(merge 95104c7 bc/fix-rebase-merge-skip later to maint).

* "git show -s" (i.e. show log message only) used to incorrectly emit
an extra blank line after a merge commit.
(merge ad2f725 mk/show-s-no-extra-blank-line-for-merges later to maint).

* "git status", even though it is a read-only operation, tries to
update the index with refreshed lstat(2) info to optimize future
accesses to the working tree opportunistically, but this could
race with a "read-write" operation that modifies the index while it
is running. Detect such a race and avoid overwriting the index.
(merge 426ddee ym/fix-opportunistic-index-update-race later to maint).

* "git status" (and "git commit") behaved as if changes in a modified
submodule are not there if submodule.*.ignore configuration is set,
which was misleading. The configuration is only to unclutter diff
output during the course of development, and not to hide
changes in the "status" output to cause the users forget to commit
them.
(merge c215d3d jl/status-added-submodule-is-never-ignored later to maint).

* Documentation for "git submodule sync" forgot to say that the subcommand
can take the "--recursive" option.
(merge 9393ae7 mc/doc-submodule-sync-recurse later to maint).